Yeah, it's unusual to see a woman with defined delts, but then again most women don't bother with the shoulders at all. If I see a woman in the gym with weights, she's usually doing leg work, benching, or working abs. Not much bi/tri/delt/trap/lat work. You can be in great cardiovascular shape, but if you don't lift weights, you're not going to get many visible striations in your upper body.

I would love to see a woman in the gym do a power clean + jerk press someday.